Fuel injection reciprocating pumps



Sept. 5, 1967 F, EHE|M ETALv 3,339,534

FUEL INJECTION RECIPROCATING PUMPS Filed March 15, 1965 2 sheets-sheet 1 ATTRNEX/a Sept. 5,' 1967 F. EHEIM ETAI.v 3,339,534

FUEL INJECTION RECPROCATING PUMPS Filed March 1s, v196.5 2 sheets-sheet 2 ATTORNEXT United States Patent Oce 3,339,534 FUEL INJECTION RECIPROCATING PUMPS Franz Eheim and Gerald Hfer, Stuttgart, Claus Kster, Unterweissach, Wurttemburg, and Horst Wegener, Kornwestheim, Wurttemburg, Germany, assignors to Robert Bosch G.m.b.H., Stuttgart, Germany Filed Mar. 15, 1965, Ser. No. 439,584

7 Claims. (Cl. 12S-140) ABSTRACT OF THE DISCLOSURE The fuel feed pump includes a shuttle for varying, during the operation of the engine fed from said pump, the fuel feed rate per stroke of the pump in accordance with variations of the number of revolutions per minute of the engine, and this by causing a variable portion of the delivery of the pump to escape without going to the engine. Means operative when the engine is started are provided to cause said shuttle to remain stationary, thus causing the whole of the delivery of the pump to be fed to the engine until the number of revolutions per minute of the engine reaches a given value.

The present invention relates to fuel injection reciprocating pumps for feeding -fuel to internal combustion engines. This invention is more especially concerned with pumps delivering, when started, a flow rate higher than that corresponding to normal operation.

There are already known pumps of this kind wherein the delivery of the pump toward the injector or injectors is normally stopped during every delivery stroke of the pump by a slide Valve called shuttle which controls a spill conduit extending from the compression chamber of the pump. This shuttle is driven toward the position for which it opens said spill conduit by means of a liquid delivered by a reciprocating auxiliary pump which works in synchronism with the fuel injection pump. This shuttle is driven in such manner that, for all normal ilow rate conditions of the pump, the opening of the spill conduit takes place before the piston of the injection pump reaches the end of its delivery stroke.

It is also known to make use of the final portion of the delivery stroke of the piston of the fuel injection pump, that is to say of the portion of this stroke which normally takes place after the opening of the spill conduit by said shuttle, to produce a flow rate ofthe pump higher than that corresponding to normal operation, and this by means of a bypass which prevents the whole or at least a portion of the liquid delivered by the auxiliary pump from driving said shuttle toward the position for which it opens said spill conduit.

The object of the present invention is to provide a fuel injection pump of the kind capable of delivering a flow rate higher than that corresponding to normal operation which is better adapted to meet the requirements of practice than those known up to this time.

The invention consists chiefly in closing said by-pass by a valve member controlled in accordance with the speed of the internal combustion engine which is fed by the fuel injection pump.

Preferred embodiments of the present invention will be hereinafter described with reference to the appended drawings, given merely by way of example, and in which:

3,339,534 Patented Sept. 5, 1967 FIG. 1 shows, diagrammatically and in axial section, the essential partsy (with the exception of the means for driving the pistons of the fuel injection pump proper and of the auxiliary pump) of a pump system according to the present invention;

FIGS. 2 and 3 similarly show two other embodiments of a fuel injection pump system according to the present invention.

The pump system includes a body 1 in which is provided the cylinder 2 of the fuel injection pump proper and the cylinder 3 of an auxiliary pump working in synchronism with said fuel injection pump proper, these two cylinders 2 and 3 being disposed coaxially in line with each other.

These cylinders cooperate with a stepped piston structure the upper part 4 of which constitutes the piston of the fuel injection pump proper whereas the lower part 5, of a diameter greater than that of part 4, constitutes the piston of the auxiliary pump. These Uwo pistons are given, through means not illustrated by the drawing, a reciprocating movement and a movement of rotation about their axis, whereby .piston 4 plays the part of a distributing valve.

There is further provided, in pump body 1, a space 6 fed by means of a transfer pump 7 (FIG. 3) with fuel the pressure of which varies in accordance with the speed of revolution of the internal combustion engine associated with the fuel injection pump, as it will be explained hereafter when describing FIG. 3.

Space 6 communicates with cylinder 2 through a feed conduit 8. This conduit 8 opens into cylinder 2 at a place such that conduit 8 is stopped at the beginning of the delivery stroke (upward stroke) of piston 4. Furthermore, in this last mentioned piston there is provided a groove 9 which extends longitudinally from the upper end face of piston 4 to the level of a plurality of delivery conduits 10 distributed about the axis of cylinder 2 and only one of which is shown by the drawing. Each of these conduits 10 feeds the fuel delivered by the pump to the injector or injectors mounted in one of the cylinders of the internal combustion engine. During every delivery stroke of piston 4, one of the conduits 10 is placed in communication with the inside of cylinder 2, so that, after a number of delivery strokes of piston 4 equal to the number of delivery conduits 10', all these conduits have been successively brought into communication rwith the inside of cylinder 2. The inside of cylinder 2 is further connected, through a spill conduit in which is interposed a regulating shuttle 11, with space 6. This spill conduit comprises a channel 12 branched to the upper end of cylinder 2, the inside of a cylinder 13 into which said channel 12 opens and, a channel 14- which connects the inside of cylinder 13 with space 6. Shuttle 11 is housed in cylinder 13 and is provided, opposite channel 12, with a groove 11a. The portions 11b and 11C of shuttle 11 located on opposite sides of groove 11a formy bearing surfaces applied in a fluid tight manner against the inner Wall of cylinder 13 while permitting the sliding of the shuttle in said cylinder 13. A spring 15 urges the shuttle toward the position shown by the drawing and which corresponds to the flange 11d of the shuttle being applied against one of the walls of the pump body 1, in which position the portion 11e of the shuttle covers the opening of channel 14 into cylinder 13 and thus closes spill conduit 12- 11a-14.

Auxiliary pump 3-5 normally serves to move shuttle 11 against the action of spring 15 to bring said shuttle into a position such that its portion 111,` clears the opening of channel 14 into cylinder 13 and thus opens spill conduit 12-11a-14, which stops the delivery of fuel into one of the delivery conduits 10 and therefore the injection into the internal combustion engine through the injector or injectors supplied by this last mentioned conduit.

The liquid that serves to transmit this movement enters cylinder 3 through a feed conduit 16 which opens into said cylinder 3 at a point cleared by piston 5 when the latter is in its lower dead center position.

During every delivery stroke of piston 5, this liquid is delivered, through one of the grooves 17 provided in the external surface of piston and through conduit 18, which is fitted with a check valve, into cylinder 13 so as to produce the stroke of shuttle 11 toward the right, except during the period for which the internal combustion engine is started, as it will be hereinafter explained.

During the period lbetween two consecutive delivery strokes of piston 5, shuttle 11 is returned by spring 15 toward its position of rest. However, the shuttle must then discharge a portion of the liquid present in cylinder 13 not through conduit 18, which is closed by the above mentioned check valve, but through a second conduit 19 which is interposed between cylinder 13 and cylinder 3. In this conduit 18 there is provided a throttled passage 20 the section of which is adjustable by means of screw 21 or the equivalent. The provision of throttled passage 20 in return conduit 19 slows down the return movement of shuttle 11 so that, from a given speed of the internal combustion engine, shuttle 11 exerts a -regulating action due to the phenomenon known under the name of liquid abutment.

Concerning the check valve provided in conduit 18, it may be of any suitable construction. For instance it comprises a slide valve 22 movable in a cylinder 23 and subjected to the action of a spring 24 which urges said slide valve 22 toward the position for which it closes conduit 178. As soon as piston 5 starts on a delivery stroke, the liquid delivered by this piston pushes slide valve 22, against the action of spring 24, until the communication is ensured between the portions of conduit 18 located respectively upstream and downstream of said slide valve 22, through passage 22a and groove 22h provided in said slide valve 22a.

The amount of fuel delivered by the piston 5 of the auxiliary pump during every delivery stroke thereof and the diameter of cylinder 13 are chosen in such manner that, normally, shuttle .11, even if it has started from its position of rest, opens spill conduit 12-11a-14 before the end of the delivery stroke of piston 4. Consequently, under normal conditions, at the end of every delivery stroke of piston 4, a portion of the fuel present in the compression chamber of pump 4-5 enters, through said spill conduit, into space 6.

At least a portion of the fuel which, normally, should thus return into space 6 is used to constitute, during the starting period, a supplementary amount of fuel delivered through conduits toward the injectors to ensure an overfeed thereof. However, such conditions of operation must stop as soon as the number of revolutions per minute of the internal combustion engine fed by the pump has reached a predetermined value which, advantageously is |lower than the idling speed of this internal combustion engine.

In order to obtain this result, there is provided, in the delivery means of the auxiliary pump 3-5, a bypass connection which, when it is open, makes at least a portion of the fuel delivered by the auxiliary pump inoperative for the displacement of the shuttle, whereby said shuttle either remains in its position of rest or, at most, has a movement insufficient for opening the spill conduit 12-11a-14. In this bypass passage, according to the rnain feature of the present invention, automatic control means are provided which are capable of closing the bypass as soon as the internal combustion engine has reached a predetermined speed.

In the embodiment of the invention illustrated by FIG. 1 the bypass consists of a channel 25 provided in shuttle 11 and opening, through a radial branch 25a, into the side surface of said shuttle 11. In the position of rest of the shuttle, radial branch 25a is located opposite a conduit 26 in communication with space 6. In this conduit 26 there is interposed a valve member consisting of a slide valve 27 provided with an annular groove 27a and slidable in a cylinder 28. A spring 29 urges slide valve 27 toward the position thereof for which groove 27a is in line with conduit 26. The bypass passage is therefore open when both shuttle 11 and slide valve 27 are in their position of rest. The position of rest of slide valve 27 is determined by an abutment 30 against which said slide valve 27 is urged by spring 29. Slide valve 27 is urged in the direction opposed to that in which spring 29 is acting thereon by the pressure of the fuel present in space 6, which pressure as above stated, is variable in accordance with the speed of the internal combustion engine fed with fuel by the pump. The force of spring 29 is determined in such manner that, when the pressure of the fuel in space 6 corresponds to said predetermined speed, which is advantageously lower than the idling speed of the internal combustion engine, this pressure is suicient for moving slide valve 27 toward the left against the action of spring 29 and for bringin-g it into a position where the bypass passage is closed. From this time on, shuttle 11 works normally, that is to say causes, at the end of every delivery stroke of piston 2, a portion of the fuel present in cylinder 2 to pass into space 6.

Obviously the value of this supplementary fuel flow rate during the starting period depends upon the internal combustion engine which is fed -by the pump. However, in many cases, the amount of fuel delivered by the pump according to the present invention to the injectors may reach, during the starting period, nearly twice the amount of fuel supplied by the injection pump under normal operation.

In some cases it is also of interest to provide a throttled pendent of erratic oscillations of the pressure in space 6, it advantageous to provide a throttled passage 31 in the conduit through which space 6 is connected with cylinder 28 so as to act upon slide valve 27.

In some cases it is also of interest to provide a throttled passage 32 in a channel 33 through which the portion of cylinder 28 where spring 29 is Ilocated is connected to a spacer under practically constant pressuure, for instance atmospheric pressure.

In the embodiment of the invention illustrated by FIG. 1, this channel 33 communicates with the space inside which is located the mechanism for driving the pump. A channel 34 connects, in an analogous manner, the portion of cylinder 23 where spring 24 is located with said space containing said mechanism.

In order to prevent the internal combustion engine from racing if, for some reason, slide valve 27 does not close the bypass passage 25-25a-26 at the desired speed of said engine, there is further provided, in this by-pass passage, a throttling intended, for higher speed of the internal cornbustion engine, and consequently for quick movements of piston 5, to cause the pressure in cylinder 13 to come to a value such that, despite the fact that the bypass passage 25-25a-26 is not closed, shuttle 11 reaches the position where it opens spill conduit 12-11a-14.

In the embodiment of FIG. l, this throttling is obtained at 35 due to a partial overlapping of the opening of conduit 26 by the portion 11b of shuttle 11 when said shuttle is in its position of rest.

The embodiment of FIG. 2 differs from that of FIG. l by the fact that the bypass passage which connects the delivery of auxiliary pump 3-5 with space 6 is disposed directly between the compression chamber of said last mentioned pump and said space 6 and that the slide valve which controls this bypass passage, instead of being disposed in series with the shuttle, is disposed in parallel therewith.

In the construction of FIG. 2, the bypass passage is essentially constituted by la channel made of two portions 36a and 36b between which is disposed a control slide valve 37 which, in its position of rest illustrated by FIG. 2, connects said portions 36a and 36b together through lan annular groove 37a provided in this slide valve, the depth of this groove being sufficiently small to enable it to act as a throttle passage provided in bypass passage 36a-36b.

Slide valve 37 is subjected, on one side thereof, to the action of the pressure existing in space 6, said pressure being transmitted through channel portion 36h and through a channel 38 branching off from said channel portion 36h and provided with a throttled passage 39 equivalent to the throttled passage 31 of FIG. 1 and, on the other side, to the action of a spring 40 which urges slide valve 37 toward its position of rest Where it is applied against abutment 41. Cylinder 47, in which slide valve 37 is housed, is connected, on the side where is located spring 40, through a channel 43, to a space where the pressure is practically equal to the atmospheric pressure (for instance to the inside of the casing in which are located the means for driving the pump). This channel 43 is provided with a throttled passage 44 the function of which is the same as that of the throttled passage 32 of FIG. 1.

It should be noted that the check valve inserted in the delivery conduit 18 of auxiliary pump 3-5 is, in the embodiment of FIG. 2 constituted by .a conventional check valve including a ball 45, but that? it might be analogous to the slide valve 22 shown in FIG. l.

The operation of the pump illustrated by FIG. 2 is quite analogous to that of the pump of FIG. 1. As long as, during the starting period of the internal combustion engine, the pump is working below a given number of reciprocation per unit of time corresponding to the number of revolutions per minute of the internal combustion engine fed by said pump, slide valve 37 remains in the position of FIG. 2 so that bypass 36a-36b is open and s-huttle 11 does not open the spill conduit 12-11a-14 and consequently the pump delivers a supplementary amount of fuel to the internal combustion engine. As soon as the number of reciprocations per unit of time of the pump has reached s-aid predetermined value, the pressure in space 6 becomes suiciently high to move slide valve 37 against the thrust of spring 40, so that bypass communication 36a-36b is stopped and shuttle 11 performs its normal regulating function.

In the embodiments of FIGS. 1 -and 2, the number of revolutions per minute of the internal combustion engine for which the slide valve that controls the bypass closes said bypass is practically the same as the number of revolutions per minute for which it opens said bypass.

The bypass should not open during the normal running of the internal combustion engine when the latter is idling and for this reason it is advantageous, according to the above described embodiments to have the bypass closed for a speed of the internal combustion engine lower thanthe idling speed thereof. However the closing of the bypass for a speed lower than the idling speed may involve some diiculties when the engine is being started, in particular from cold. This is why it is often useful to have the bypass closed, during the starting period, only when the internal combustion engine has reached a speed higher than the idling speed and to prevent a reopening of the bypass only when the number of revolutions per minute of the internal combustion engine has become lower than the idling speed. The embodiment of FIG. `3 complies with this condition. Furthermore it has the advantage of ensuring very quick movements of the slide valve when it opens or closes 'the bypass.

The embodiment of FIG. 3 corresponds to the principle of operation of the embodiment of FIG. 2 but comprises different means for producing the opening and the closing of slide valve 37, respectively. Furthermore, FIG. 3

illustrates the means through which there is obtained, in space 6, a pressure variable with the number of revolutions per minute of the engine fed with fuel by the injection pump. It should be noted that such means also apply to the constructions of FIGS. 1 and 2.

The means in question'include, as above stated, a transfer pump 7, for instance a gear pump. This pump sucks in fuel from a tank, not shown, with which it communicates through a suction conduit 46a and it delivers fuel into space 6 through a delivery conduit 46b. From said space 6 branches off a return conduit 47 through which a portion of the fuel delivered by pump 7 can ow back to suction conduit 46a. In this return conduit 47 there is provided a throttled passage 48. The cross section of said throttled passage 48 may be fixed. However, preferably, as shown, this cross section is variable and controlled in a known manner, for instance by means of a piston 49 which, under the action of the deliverypressure of pump 7 -and against the action of a spring 50, controls the cross section of throttled passage 48 so as to increase it when the delivery pressure of pump 7 increases.

The bypass passage Sla-51h connects the delivery conduit 1S of auxiliary pump 3-5 with the delivery conduit 46b of pump 7 which, as above stated, leads to space 6. Between the portions 51a and 511) of this bypass passage the control slide valve 37 is interposed. Due t0 its small depth, `groove 37a, forms a throttled passage in said bypass passage Sla-SIb. Of course, this bypass passage Sla-SIb might as well be branched directly on the compression chamber of auxiliary pump 3-5, according to the arrangement illustrated by FIG. 2.

One side of slide valve 37 is subjected to the action of the delivery pressure of pump 7, that is to say of the pressure existing in space 6, through a channel 52 branching off from the portion 51b of the bypass passage, said channel 52 being provided with a throttled passage 53. The other side of slide valve 37 is subjected to the action of a spring 54. Furthermore, the space 55 in which said spring 54 is located is connected, through a conduit 56 including a throttled passage 57, with the suction conduit 46a of transfer pump 7.

In order to obtain the above mentioned particular operation, space 55 is further connected, through a channel 58, provided with a throttled passage 59, with the portion 51b of the bypass passage. The opening of conduit 58 into space 55 is located at a place such that it is closed by slide valve 37 as'soon as said slide valve leaves its position of rest illustrated by FIG. 3 under the action of the increase of the delivery pressure of pump 7.

Throttled passage 59 may be located at the place where channel 58 opens into space 55.

The operation of slide valve 37 is as follows:

When the internal combustion engine is being started, slide valve 37 is in the position illustrated by FIG. 3 where it clears bypass passage Sla-51h. The force that tends to move slide valve 37 toward the left consists in the fuel pressure which, throu-gh channel 52, acts upon the right hand side of slide valve 37. This force is however weakened by the fact that a portion of the fuel delivered by pump 7 into the portion 51h of the bypass passage can escaperthrough channel 58 into space 55', located on the left hand side of slide valve 37 and thence into conduit 56. On the other hand, the force which tends to keep slide valve 37 in the position where the bypass passage is open consists not only of the `force exerted by spring 54 but also of the pressure of the liquid entering into space 55 through channel 58, which pressure, owing to the eifect of throttled passage 57, is higher than the pressure existing in conduit 56. which is connected to suction conduit 46a.

The pressure acting upon the right hand side of slide valve 37 must therefore reach a valve corresponding to a speed of the internal combustion engine higher than its idling speed for causing slide valve 37 to start upon its movement toward the left against the action of spring 54 and of the pressure existing in space 55. However, as soon as slide valve 37 has started upon said movement, it closes the throttled opening 59 of conduit 58, which produces a quick and complete closing of bypass passage Sla-SIb, This quick closing is due to the fact that the stopping of the throttled passage 59 of channel 58 produces, on the one hand, an increase of the pressure acting upon the right hand side of slide valve 37, and on the other hand a reduction of the pressure existing in space 55.

Once bypass passage Sla-SIb has been closed by slide valve 37 at the end of the starting period of the internal combustion engine, reopening of said bypass passage under the action of spring 54 can take place only when the pressure action upon the right hand side of slide valve 37 has become much lower than the pressure which was necessary for moving slide valve 37 into its closing position. This is due to the fact that this reopening can take place only when, due to a slowing down of the internal combustion engine, the pressure acting upon the right hand side of slide valve 37 (which pressure is not then reduced by the opening of channel 58) has become so low that spring 54 alone is capable of producing the displacement of slide valve 37 toward the right. As soon as, at the beginning of this movement, slide valve 37 has cleared the opening 59 of channel 58, the remainder of the opening displacement of slide valve 37 takes place at high speed since, due to clearing of said opening 59, on the one hand the pressure acting upon the right hand side of slide valve 37 decreases suddenly, and, On the other hand, the force tending to move slide valve 37 toward the right is increased because, to the force of spring 54, there is added the pressure of the liquid entering through passage 59 into space 55.

-By a suitable choice of the force of spring 54 and 0f the cross sections of throttled passages 57 and 59, it is possible to obtain that the closing of the bypass passage Sla-SIb, after the starting of the internal combustion engine, takes place only for a speed of said engine much higher than the idling speed thereof, whereas the reopening of said bypass passage Sla-51h can take place only when the number of revolutions per minute of the internal combustion engine has dropped below the idling speed of this engine.

Of course the function of the slide val-ve that controls the bypass passage may be performed by the same element which serves to determine the `free cross section of throttled passage in conduit 19, through which the shuttle, during its return stroke, delivers liquid in such manner that said return stroke is braked. In this case, said element may consist of a slide valve which, in the position where it closes the bypass passage, gives the throttled passage in conduit 19 the desired cross section.

In a general manner, while the above description, discloses what are deemed to be practical and efficient embodiments of the present invention, said invention is not limited thereto, as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the invention as comprehended within the scope of the appended claims.

What is claimed is:

1. For use with an internal combustion engine, a pump for feeding fuel to said engine which comprises, in combination,

a fixed frame,

a main cylinder rigid with said frame,

a main piston slidable in said cylinder so as to limit therewith a variable volume main pump chamber, at least one delivery conduit starting from said pump chamber,

an auxiliary cylinder rigid with said frame,

an auxiliary piston slidable in said auxiliary cylinder in synchronism with the movement of said main piston in said main cylinder, said auxiliary piston limiting with said auxiliary cylinder a variable volume auxiliary pump chamber,

a structure forming a cylindrical housing fixed with respect to said frame,

a shuttle slidable in said housing, said shuttle limiting in said housing a variable volume shuttle chamber,

a first conduit extending from said auxiliary pump chamber to said shuttle chamber,

means for permitting the ow of liquid through said first conduit only in the direction from said auxiliary pump chamber to said shuttle chamber,

a second conduit extending from said shuttle chamber to said auxiliary pump chamber,

means in said second conduit forming a throttled passage,

means fixed with respect to said frame forming a closed space, l

means for placing said closed space under a pressure variable in accordance with the number of revolutions per minute of said internal combustion engine,

spring means for urging said shuttle in the direction for which the volume of said shuttle chamber is reduced,

a first spill conduit element forming a communication between said main pump chamber and said shuttle housing,

a second spill conduit element forming a communication between said shuttle housing and said space,

said shuttle being shaped to connect said spill conduit elements together in response to an increase of the Volume of said shuttle chamber,

conduit means for connecting said auxiliary pump chamber with said space to prevent the action of said auxiliary pump on said shuttle,

valve means in said conduit means for the opening and `closing thereof, and

means responsive to variations of the number of revolutions per unit of time of said internal combustion engine for bringing said valve means into conduit means opening position for low values of said number of revolutions per unit of time and into conduit means closing position for higher values of said number of revolutions per unit of time.

2. A pump according to claim 1 wherein said valve means is a slide valve movable in a housing of said frame, the means recited in the last paragraph of claim 1 including:

resilient ymeans interposed between said frame and said slide valve for urging said slide valve toward opening position, and

`means for transmitting to one side of said slide valve the pressure in said closed space to oppose the action of said resilient means on said slide valve.

3. A pump according to claim 2 wherein a throttled passage is provided in said means for transmitting to one side of said slide valve the pressure in said closed space.

4. A pump according to claim 2 wherein said conduit means include said first conduit, said shuttle chamber, a passage extending through said shuttle and a conduit in said frame across which extends said slide valve,

said shuttle being arranged so that, in the position thereof for which said shuttle chamber has the minimum volume, it forms with its housing a throttled passage in said conduit means.

5. A pump according to claim 2 wherein said conduit means extend ldirectly from said auxiliary pump chamber to said space, said slide valve extending across said conduit means.

6. A fuel feed pump according to claim 5 further comprising a communication channel between on the one hand the portion of said conduit means located between said space and said slide valve and, on the other hand, the end of said second mentioned housing where is located said resilient means, said communication channel including a throttled passage, the opening of said communica- 9 10 tion channel into said housing being located so as to be References Cited left open by said slide valve as long as said slide valve is in the position Where it leaves said conduit means open UNITED STATES PATENTS and to 'be closed 'by said slide valve as soon as said slide 3,025,797 3/ 1962 Hutcheon 10S- 2.1 X

valve starts moving toward the position Where it closes 5 3,163,042 said conduit means.

7. A pump according to claim 5 wherein said slide valve is provided, to connect the portions of said conduit MARK NEWMAN Primary Exammer' means extending on either side of said valve, with a groove LAURENCE M GOODRIDGE, Examiner, of sufficiently small depth to form a throttled passage. 10

2/ 1965 Bessiere 103-2.1 

1. FOR USE WITH AN INTERNAL COMBUSTION ENGINE, A PUMP FOR FEEDING FUEL TO SAID ENGINE WHICH COMPRISES, IN COMBINATION, A FIXED FRAME, A MAIN CYLINDER RIGID WITH SAID FRAME, A MAIN PISTON SLIDABLE IN SAID CYLINDER SO AS TO LIMIT THEREWITH A VARIABLE VOLUME MAIN PUMP CHAMBER, AT LEAST ONE DELIVERY CONDUIT STARTING FROM SAID PUMP CHAMBER, AN AUXILIARY CYLINDER RIGID WITH SAID FRAME, AN AUXILIARY PISTON SLIDABLE IN SAID AUXILIARY CYLINDER IN SYNCHRONISM WITH THE MOVEMENT OF SAID MAIN PISTON IN SAID MAIN CYLINDER, SAID AUXILIARY PISTON LIMITING WITH SAID AUXILIARY CYLINDER A VARIABLE VOLUME AUXILIARY PUMP CHAMBER, A STRUCTURE FORMING A CYLINDRICAL HOUSING FIXED WITH RESPECT TO SAID FRAME, A SHUTTLE SLIDABLE IN SAID HOUSING, SAID SHUTTLE LIMITING IN SAID HOUSING A VARIABLE VOLUME SHUTTLE CHAMBER, A FIRST CONDUIT EXTENDING FROM SAID AUXILIARY PUMP CHAMBER TO SAID SHUTTLE CHAMBER, MEANS FOR PERMITTING THE FLOW OF LIQUID THROUGH SAID FIRST CONDUIT ONLY IN THE DIRECTION FROM SAID AUXILIARY PUMP CHAMBER TO SAID SHUTTLE CHAMBER, A SECOND CONDUIT EXTENDING FROM SAID SHUTTLE CHAMBER TO SAID AUXILIARY PUMP CHAMBER, MEANS IN SAID SECOND CONDUIT FORMING A THROTTLED PASSAGE, MEANS FIXED WITH RESPECT TO SAID FRAME FORMING A CLOSED SPACE, MEANS FOR PLACING SAID CLOSED SPACE UNDER A PRESSURE VARIABLE IN ACCORDANCE WITH THE NUMBER OF REVOLUTIONS PER MINUTE OF SAID INTERNAL COMBUSTION ENGINE, SAID SPRING MEANS FOR URGING SAID SHUTTLE IN THE DIRECTION FOR WHICH THE VOLUME OF SAID SHUTTLE CHAMBER IS REDUCED, A FIRST SPILL CONDUIT ELEMENT FORMING A COMMUNICATION BETWEEN SAID MAIN PUMP CHAMBER AND SAID SHUTTLE HOUSING, A SECOND SPILL CONDUIT ELEMENT FORMING A COMMUNICATION BETWEEN SAID SHUTTLE HOUSING AND SAID SPACE, SAID SHUTTLE BEING SHAPED TO CONNECT SAID SPILL CONDUIT ELEMENTS TOGETHER IN RESPONSE TO AN INCREASE OF THE VOLUME OF SAID SHUTTLE CHAMBER, CONDUIT MEANS FOR CONNECTING SAID AUXILIARY PUMP CHAMBER WITH SAID SPACE TO PREVENT THE ACTION OF SAID AUXILIARY PUMP ON SAID SHUTTLE, VALVE MEANS IN SAID CONDUIT MEANS FOR THE OPENING AND CLOSING THEREOF, AND MEANS RESPONSIVE TO VARIATIONS OF THE NUMBER OF REVOLUTIONS PER UNIT OF TIME OF SAID INTERNAL COMBUSTION ENGINE FOR BRINGING SAID VALVE MEANS INTO CONDUIT MEANS OPENING POSITION FOR LOW VALUES OF SAID NUMBER OF REVOLUTIONS PER UNIT OF TIME AND INTO CONDUIT MEANS CLOSING POSITION FOR HIGHER VALUES OF SAID NUMBER OF REVOLUTIONS PER UNIT OF TIME. 